Have you tried citronella oil? That's a pretty powerful pest deterrent. I use it when I go camping and it works well (I tend to attract mosquitoes within a 50 mile radius usually! LOL)
There is a great natural produce available here in Hawaii called Waikoloa Bob's Hawaiian Botanical Oil, it works great here and should do in India also.Website address is www.waikoloabob.com it has canola and sunflower oil, lemon grass, tea tree, citronella, and the active ingredient is essential oil of Nepeta Cataria.
See if they will send you a bottle, it goes a long way and is really good here. If they won't send you some let me know and I'll mail a bottle to you to try.
Long term you just have to be as healthy and fit as possible, be light! Sleep under mozzie nets, be careful during dusk and dawn etc.. Long term repellants are not sustainable or practical, and having lived in the tropics most of my life in New Guinea and the Solomon Islands, you really just have to face up to the instabilities of this climate. I've had malaria around a dozen times so I know loads about mosquito parasites, the best solution is radiant light health, in body, mind and spirit.
Yep, thats the only way! Get your immunesystem strong!